Piercing battle damage is battle damage dealt by a card effect to the controller of a Defense Position monster by an attacking monster. If the defending monster's DEF is lower than the attacking monster's ATK, the difference is inflicted as battle damage. It is occasionally referred to unofficially as "trample" damage, due to that term having a similar meaning in Magic: The Gathering.

Because some Equip Spell Cards that allow monsters to inflict piercing damage deal damage to the opponent of the controller of the Equip Spell Card rather than the opponent of the controller of the monster, if a player equips a card like "Fairy Meteor Crush" to an opponent's monster and the opponent attacks the player's Defense Position monster, the opponent will take battle damage instead of the player.